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Grant's Gazelle
Grant’s gazelles are often found in small herds of up to 30, with an adult ram controlling a territory, and a group of ewes and their offspring roaming over larger areas than the male. Younger and non-territorial rams may form bachelor groups that move around the edges of territorial ram ranges. However, these groupings are not fixed, and Grant’s gazelles deal with changing food supplies by having an exceptionally fluid social system. When there is an adequate supply of food all year round, rams maintain territories continually. In other areas they tend to be nomadic, moving from high, well-drained areas during the rains, to flat, grassy valleys in the dry season, with larger temporary herds forming at certain times of the year. The Grant’s gazelle prefers to eat herbs and shrub foliage, but will also graze on grass during the early rains when it is young and green. It is often found feeding with other herbivores, benefiting from other animals feeding on the grass, as this encourages the growth of herbs on which the gazelles primarily feed. Adult territorial rams mark their area with dung and urine deposits and perform elaborate displays when confronting each other, particularly during the biannual mating peaks. The displays involve a characteristic flicking of the raised head; slow, stiff head-circling; and lowering the head with the horns pointing at the opponent. Births follow a six month gestation and the fawn, weighing five to seven kilograms, remains hidden for the first few weeks of life. Description The most distinguishing feature of this pale fawn gazelle is the distinct vertical black stripe that runs down either side of the white buttocks. The underparts and inner legs are also white, and the tail is white at the base but has longer black hair towards the tip. Its magnificent horns are long, ringed and slope slightly backwards and outwards, with the tips pointing inwards. The lighter females have considerably shorter and more slender horns, and several subspecies of Grant’s gazelle are recognised based on the shape of the horns. The eyes are set in leaf-shaped, jet-black patches of skin, incorporating the preorbital glands that, unlike other gazelle species, the Grant’s gazelle does not use to mark territories. Ecology and Behavior The Grant's gazelle is found in East Africa and lives in open grass plains and is frequently found in shrublands; it avoids areas with high grass where the visibility of predators is compromised. They also occur in semiarid areas and are relatively well adapted to dry areas, relying on more browse or leafy material during dry seasons to supplement their intake of water. They are migratory animals, but travel in the opposite direction of most of the other ungulates, such as Thomson's gazelles, zebras, and wildebeest, which are more water dependent. They can subsist on vegetation in waterless, semiarid areas, where they face little competition. The most common predators of the Grant's gazelle are cheetahs and wilddogs. Humans also tend to hunt gazelles. In the Serengeti, Grant's gazelle is a prey item for cheetahs, but the Thomson's gazelle is preferred. However, in Nairobi National Park, Grant's gazelle is preferred over Thomson's gazelle, making it an important resource to the cheetah.[ Jackals are major predators of fawns. The Grant's gazelle is a gregarious, territorial, and migratory species. The home ranges of does overlap with those of the bucks. Only male gazelles are territorial. Male gazelles will herd all females that cross their territories. When the females are in estrus, they are strongly guarded by the dominant male, which prevents other males from mating with them. Any doe that tries to leave is aggressively herded back. Most of the time, the buck’s simple stance in relation to her is enough to keep the female from leaving. Bachelor groups are made up of adolescent and bucks not holding territory. Any new members must perform intimidation displays to enter the group. However, bachelor groups tend to be very loose and members can leave whenever they want. The larger, older males with thick horns have the best chance of establishing a territory. Conflicts between adult males are usually solved with intimidation displays. The bucks circle each other and swing their necks from side to side, displaying their neck power. Neck strength is important in an actual fight and the male that cannot keep up yields. Gazelles of nearly equal neck strength are more likely to engage in actual combat. Fighting occurs in young bucks more often than older ones. Dominant bucks can simply run off subordinates rather than having to display to them. Diet Grant’s gazelles are generally mixed feeders that both browse and graze. Their average diet consists of 65.8% browse and 34.3% graze. Rainfall in their habitats seems to be the determinant of their diets.13 The Grant's gazelle's diet may also be responsible for the slow growth rates in the browsed plots.14 They get most of their moisture from the plants they eat, so they do not often have to drink water. Thus they can stay on the plains long after the rains end. From July to September, gazelles move deep into dense brush and wait for the next rains. They will eat red oats and small, tough plants, which are avoided by the other ungulates. This allows the gazelles to survive in the brush during the dry season. Grant’s gazelles eat mainly dicotyledons during the dry season and grass in the wet season. Reproduction Grant’s gazelles sexually mature at 18 months. Territory-holding bucks mate more than ones in bachelor groups. The courting ritual begins with a buck following a doe, waiting for her to urinate. When she does, the male does the Flehmen response to determine if she is in estrus. If she is, he will continue to follow her. The female will lift her tail, signaling she is ready to mate, and the male will mount her. The gestation period for the gazelle lasts for 198 days. Births peak in January and February. A doe will leave her herd and find a well-hidden place to give birth. Afterwards, the female eats the afterbirth and other fluids to keep the fawn clean and scentless. Females that have recently given birth will stay together for protection. The does nurse their fawns four times a day. Fawns are immobile for the first few days, so the mother stays close by. When the fawn can walk, it leaves with its mother to find a herd. Around this time, fawns will associate with one another in peer groups. A gazelle is weaned at six months, but will continue to associate with its mother until adolescence. Category:Mammals Category:Herbivores Category:Antelope Category:African-Animals Category:Gazelles